This invention relates to pipework.
This invention is particularly concerned with junctions in pipework for heat transport systems using liquid sodium as seen, for example, in fast fission nuclear reactors.
One of the problems involved with sodium-conducting pipework is that of thermal shock. The heat transfer capacity of sodium is so high that a sudden change of sodium temperature (such as may arise from a reactor trip) would give rise to severe stresses. The problem is ameliorated to some extent by the fact that the sodium is usually not operating at any substantial pressure and hence pipework, for the most part, can be of thin wall and hence is more tolerant to sudden temperature changes. However, this amelioration is not so significant at junctions where it may be essential to thicken the pipe wall to accommodate mechanical working during manufacture and where other stresses might have to be met such as those arising from pipework thermal expansion loadings or restraints on the pipes at the junction.